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Earth's Atmosphere/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby Tim and Moby are seated next to each other on a plane. Tim is next to the window. Moby presses a button on his armrest, and a flight attendant brings him a drink. A typed letter outside the plane flies up and sticks to Tim's window. TIM: Aaah! Creepy. Tim reads from the typed letter. TIM: Dear Tim and Moby, What is the atmosphere? Why is the sky blue? From, Thomas. The atmosphere is made up of a mixture of gases, mostly nitrogen and oxygen, that wrap around the earth like a blanket. An animation shows Earth and its atmosphere from space. A circle graph indicates that most of Earth's atmosphere is nitrogen, the next most prevalent gas is oxygen, and a very small percentage of it is other gases, including argon and carbon dioxide. TIM: Without the atmosphere, we wouldn't be able to live here. Those gases protect us by blocking out dangerous rays from the sun and making Earth a perfect habitat for plants and animals. An animation shows the sun shining on a wooded area, with animals, insects, and flowers. TIM: The earth's atmosphere has five layers: the troposphere, the stratosphere, the mesosphere, the thermosphere, and the exosphere. An animation shows the layers of the atmosphere from the ground to outer space. The troposphere is closest to the ground, and the exosphere is farthest from the ground. A plane, a weather balloon, and a satellite float by in different layers. TIM: Atmospheric gases become thinner the higher up you go. The troposphere is the lowest layer. It's also known as the weather layer, since rain, snow, and wind stick to this layer. An animation shows white clouds in a blue sky. Other animations represent rain, snow, and wind. TIM: The troposphere extends sixteen kilometers above ground at the equator and eight kilometers at the poles. An animation shows Earth from space, along with the sun. Arrows and graphics illustrate the location of the troposphere as Tim describes it. TIM: From the top of the troposphere to fifty kilometers above ground lies Earth's stratosphere, where the temperatures increase with altitude. An animation shows the location of the stratosphere as Tim describes it. A weather balloon is floating at this level. TIM: It starts out at minus sixty degrees Celsius at the bottom and then warms to about freezing. An animation shows a mercury thermometer. Its readings change to illustrate the temperatures Tim is describing. TIM: This happens because the stratosphere is heated from above by the sun's ultraviolet radiation. An animation shows the earth and the sun from space. Squiggly lines from the sun represent ultraviolet radiation reaching the stratosphere. TIM: The ozone layer is found in the stratosphere. Ozone is a gas that absorbs harmful UV rays and protects us from too much solar radiation. An animation represents ozone gas and how it absorbs UV rays. TIM: Pollution has created holes in the ozone layer over the North and South poles. A flight attendant gives Moby a set of headphones. TIM: The earth's mesosphere is found starting at fifty kilometers above ground. An animation shows the location of Earth's mesosphere. TIM: The atmosphere reaches its coldest temperature of around minus ninety degrees Celsius in the mesosphere. This is also the layer in which a lot of meteors disintegrate from friction while entering the earth's atmosphere. An animation shows Earth from space. Meteors enter Earth's atmosphere and disintegrate as Tim describes. TIM: The thermosphere is the fourth layer of the earth's atmosphere and also the hottest. An animation shows the location of Earth's thermosphere. TIM: The air is so thin that not much solar radiation can be absorbed, and temperatures climb to almost two thousand degrees Celsius. The Earth's thermosphere also includes the ionosphere, a region of the atmosphere that's filled with charged particles. An animation represents charged particles in the ionosphere. TIM: Starting five hundred kilometers above Earth, the exosphere is the highest layer of our atmosphere. An animation illustrates the location of Earth's exosphere. TIM: It is definitely not stable. The atmosphere becomes very thin and gas molecules can escape into space. An animation represents gas molecules in the exosphere. MOBY: Beep. Moby is pressing the button on his armrest again. TIM: Oh, right, why is the sky blue? Well, light has different colors based on its wavelength. An animation shows wavy lines in different colors, representing different wavelengths of light. TIM: The gases in our atmosphere scatter certain wavelengths of light and let others pass right through. Blue light is scattered the most efficiently by the gases in our atmosphere. That's why the sky appears to be blue. The color of light that gets through our atmosphere most is blue. Therefore, we have a blue sky. The wavelength animation shows how blue scatters by showing it disappearing. An image shows a wooded area and a blue sky above it. A flight attendant brings Moby a pillow and then leaves. Moby keeps pressing his armrest button over and over. TIM: Hey, leave that flight attendant alone. Category:BrainPOP Transcripts Category:BrainPOP Science Transcripts